Human Impacts on Soil Health Are the Bugs Bugged? The Effect of Deforestation on Land Dwelling...
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Transcript of Human Impacts on Soil Health Are the Bugs Bugged? The Effect of Deforestation on Land Dwelling...
BackgroundInsects perform critical functions in our environment- nutrient recycling--plant, animal, and dung
decomposition, and fungi dispersal- plant propagation- food for higher animals- maintenance of plant and animal
communities
Background
Their presence is needed for a healthy environment
If they are absent, an inference can be made on the health of the land
Because of this, Conservation biologists use insects for environmental monitoring
Also, they are easy and inexpensive to study
Initial Model
Arthropods
Humans
Development/Deforestation
Determine the level and location
Affects the lives (breeding locations, food, growth media) of
Create a habitable environment for
Breaks down
Gives convenience to their lives
Contribute to food sources for
Portion included in this study
AssumptionsInsects do describe the health of the land
The more insects there are, and the more diverse the present species, the healthier the land
Insects at one site would be similar to a nearby site if their environments were made the same
Insects present during the fall describe the insect population of the land
Methods
Chose sites
Collected arthropods- Dug hole size of spaghetti sauce jar- Placed jar in hole- rim flush with ground- Left for 72 hours- Collected jars, counted, and identified
trapped arthropods
DataInsect Abundance Across Sites
02468
10121416
High Mild Low
Level of Deforestation
Nu
mb
er
of
Sp
eci
me
ns
Species Diversity
0
2
4
6
8
10
High Mild Low
Level Of Deforestation
Nu
mb
er
of
Sp
eci
es
DataSite Kind of Species Found NicheHighlyDeforested Site
Very small, unidentifiablearthropod(nickname, “Sim”)
Unknown
MildlyDeforested Site
3 Arachnids6 Pill bugs6 Earwigs (Dermaptera)13 “Sims”1 Campodea (Diplura)
PredatorHerbivoreHerbivoreUnknownHerbivore
LowDeforested Site
2 Beetle3 Earwigs1 Milipede1 “Sim”1 Pillbug3 Mites3 Campodea
UnknownHerbivoreUnknownUnknownHerbivoreUnknownHerbivore
Conclusions and ClaimsSpecies diversity, and diverse niches filled decreases with increased deforestation
Deforestation disturbs insect populations
The disturbed insect population cannot support the land for higher animals and plants
Deforested areas are unable to support plant and animal life
One result as deforestation occurs; animal populations are forced to move, impeding on the population’s growth and survival
Revised model
Arthropods
Humans
Development/Deforestation
Determine the level and location
Affects the lives (breeding locations, food, growth media) ofDecreasing species diversity and ecological functions performed
Create a habitable environment for
Breaks down
Gives convenience to their lives
Contribute to food sources for
More QuestionsWhat would these sites look like in the spring or summer?
What other kinds of insects are present that I couldn’t catch?
Which insects are most helpful in nutrient recyling in our area?
Which insects support the lives of vertebrates most?
Can the introduction of insects be used in restoration of land?
What is the relationship What is the relationship between bugs and the between bugs and the nutrients in the soil in nutrients in the soil in
compost piles?compost piles?Rachelle LoukRachelle Louk
Edtep 586Edtep 586
Autumn 2004Autumn 2004
Initial ModelInitial Model
Niche differentiationNiche differentiation Niche interaction Niche interaction Differential Differential
distribution of distribution of speciesspecies
Species vary with Species vary with level of level of decompositiondecomposition
About compost piles:About compost piles:
The interior of a compost pile is warmer The interior of a compost pile is warmer than the exteriorthan the exterior
The top of a pile is less compact than the The top of a pile is less compact than the bottombottom
Level of decomposition increases towards Level of decomposition increases towards the bottom of a pilethe bottom of a pile
As decomposition progresses, organic As decomposition progresses, organic compounds will be returned to the soil - compounds will be returned to the soil - nitrogen in particularnitrogen in particular
Definition of bug:Definition of bug:
I am using the word ‘bug’ to include all I am using the word ‘bug’ to include all of the macro-invertebrates that I of the macro-invertebrates that I observed. This includes organisms observed. This includes organisms from the phyla:from the phyla:ArthropodaArthropodaAnnelidaAnnelidaNematodaNematoda
AssumptionsAssumptions
That bugs would be present in all samplesThat bugs would be present in all samples(this turned out to be problematic)(this turned out to be problematic)
That a given level of a pile is homogeneous That a given level of a pile is homogeneous enough to yield representative samplesenough to yield representative samples
Level of decomposition and position in pile are the Level of decomposition and position in pile are the main factors affecting bug distribution and main factors affecting bug distribution and abundanceabundance(materials in pile affect bugs present)(materials in pile affect bugs present)(pH affects the bacteria/fungi present, which (pH affects the bacteria/fungi present, which
affect bugs that graze on bacteria/fungi)affect bugs that graze on bacteria/fungi)
MethodsMethods
Collect samples of compost from top, middle, Collect samples of compost from top, middle, and bottom of piles using 4 fl.oz. plastic and bottom of piles using 4 fl.oz. plastic containercontainer
Use a dissecting scope to search a petri dish Use a dissecting scope to search a petri dish full of compost from each samplefull of compost from each sample
Isolate bugs in vials with ethanolIsolate bugs in vials with ethanol Identify bugs and research nichesIdentify bugs and research niches Test samples for N content using Rapitest® Test samples for N content using Rapitest®
soil kitsoil kit
Some of the cool bugs I Some of the cool bugs I found...
PseudoscorpionPseudoscorpion Oribatidae MiteOribatidae Mite
Collembola (aka springtails)Collembola (aka springtails)
CentipedeCentipede
Niches of the bugs:Niches of the bugs:
The detritivores I The detritivores I found include:found include: collembola (a.k.a. collembola (a.k.a.
springtails)springtails) isopods (a.k.a. potato isopods (a.k.a. potato
bugs)bugs) dipluransdiplurans millipedesmillipedes annelids (a.k.a. earth annelids (a.k.a. earth
worms)worms)
The predators I The predators I found include:found include: pseudoscorpionspseudoscorpions oribatidae mitesoribatidae mites staphylinidae beetlesstaphylinidae beetles centipedescentipedes fly larvaefly larvae nematodes (a.k.a. round nematodes (a.k.a. round
worms)worms)
Most of the bugs I found were generalists and Most of the bugs I found were generalists and mostly competing for the same food sources. This mostly competing for the same food sources. This data refutes my initial hypothesis that competition data refutes my initial hypothesis that competition
would be minimized by niche differentiation.would be minimized by niche differentiation.
Bug population composition Bug population composition across UW greenhouse pileacross UW greenhouse pile
0
5
10
15
20
25
30
35
40
top middle bottom
Location of sample in pile
Nu
mb
er
of
bu
gs
worm
millipede
centipede
isopods
orobatidae
collembola
More bugs and more types of bugs mid- More bugs and more types of bugs mid- pile, least number of bugs at the bottompile, least number of bugs at the bottom
Bug population composition Bug population composition across horse manure across horse manure
compostcompost
More bugs at the bottom/oldest part of the pileMore bugs at the bottom/oldest part of the pile
0
5
10
15
20
25
30
top (7-9 mos) middle(12mos)
bottom(15mos)
Location and Age of Sample
Nu
mb
er
of
bu
gs
earth worms
nematodes
fly larvae
pseudoscorpion
orobatidae mites
collembola
Bug population distribution in 15 Bug population distribution in 15 month old piles of varying month old piles of varying
compositioncomposition
More bugs, and types of bugs, in mixed More bugs, and types of bugs, in mixed compostcompost
0
10
20
30
40
50
60
chickenmanure
horse manure horse manure+ garden
wasteComposition
Nu
mb
er
of
Bu
gs
fly larvae
pseudoscorpion
earthworm
nematodes
oribatidae mites
staphylinidae beetle
dipluran
collembola
isopods
Bug distribution across piles and positions
Some groups have nearly ubiquitous distribution, and Some groups have nearly ubiquitous distribution, and some show localized distribution. However, the some show localized distribution. However, the distribution of most of these bugs do not suggest distribution of most of these bugs do not suggest differential distribution within compost piles. differential distribution within compost piles.
0102030405060
Nu
mb
er
of
bu
gs millipede
centipede
fly larvae
nematodes
annelids
pseudoscorpions
diplura
staphylinidae
oribatidae
collembola
isopods
greenhousegreenhouse Chicken manureChicken manure Horse manureHorse manure
Relative nitrogen levels Relative nitrogen levels across piles and locationsacross piles and locations
012345678
gree
nous
e,to
p of
pile
gree
nhou
se,
bott
om o
fpi
le
2 yr
chi
cken
man
ure
+di
rt
7-9
mos
hors
em
anur
e, t
op
12 m
osho
rse
man
ure,
Re
lati
ve N
co
nce
ntr
ati
on
Concentrations were compared to N2=adequate, N3=sufficient, N4=surplus. Concentrations were compared to N2=adequate, N3=sufficient, N4=surplus. Concentrations higher than N4 were assigned a level relative to other readingsConcentrations higher than N4 were assigned a level relative to other readingswith an increasing scale of 0.5 determined arbitrarily. with an increasing scale of 0.5 determined arbitrarily. Nitrogen concentrations generally increased with the Nitrogen concentrations generally increased with the age of the sample.age of the sample.The starting material of the pile affected the The starting material of the pile affected the concentration of nitrogen. concentration of nitrogen.
Evidence & Final ClaimsEvidence & Final Claims
Most of the bugs I found were generalists and Most of the bugs I found were generalists and mostly competing for the same food sources, mostly competing for the same food sources, refuting a hypothesis of niche differentiation.refuting a hypothesis of niche differentiation.
I found no conclusive evidence of differential I found no conclusive evidence of differential distribution of bugs within piles. distribution of bugs within piles.
More bugs, and types of bugs, in compost of mixed More bugs, and types of bugs, in compost of mixed composition. The materials in the environment composition. The materials in the environment influence the presence of bugs.influence the presence of bugs.
Nitrogen concentrations generally increased with Nitrogen concentrations generally increased with the age of the sample and was effected by the the age of the sample and was effected by the composition of the pile. composition of the pile.
Future Questions...
Were my samples representative?I’d like to do it again taking multiple
samples at every level.
Did pH, or any other nutrient effect the bugs present?
Does population composition vary seasonally?
I want to thank:
UW Biology Department:Eileen O’Connor for helping me arrange lab
time and equipmentEvan Sugden for identifying bugs for me
Good entomology websites at:University of MissouriUniversity of Nebraska - Lincoln
My colleagues for academic and emotional support!
Invertebrates as Indicators of Human Impact on Soil
“How do invertebrate populations change with soil compaction?”
My First ModelInitial Question:
How are surface and underground bug populations different in areas that have experienced industrial pollution versus areas that have experienced mild human development and areas relatively
undeveloped and not exposed to recent pollution or human activity?
Hum
an Impact
As
Bug S
pecies Diversity
Exposure to P
ollution
And
Ratified Ideas
Failure to collect sufficient data indicating site pollution history
combined with faulty data collection techniques
Resulted in a revised question and model
Revised Model:
Question:
Are insect populations different in habitats characterized by serious, moderate and minimal soil compaction? Which insects survive better in areas with soil compaction?
Human Activity
Soil Compaction
Aeration
Drainage
Nutrient Content
Insect Population/Diversity
Assumptions
1. Invertebrates could be used as an indicator species for soil compaction
2. Soil density is a measure of compaction
3. Soil sample collection method is accurate enough to determine relative density of various soil samples
A little background…In a study by Lindo and Visser it was determined that certain species of micro-arthropods could be used as an indicator species for human disturbance in the form of forest clear cutting and that the factors most likely influencing the changes in species diversity and abundance are soil compaction and changes in food availability
Significance…Study findings may support assumption #1 that invertebrates can be used as an indicator of soil compaction
Site Selection
Three locations at Discovery Park suspected of having different soil densities were selected for this experiment.
Site #1on a main path leading from the visitor’s center to the loop trail
Site #2 on a less popular path leading behind the visitor’s center
Site #3 located 30 paces off the path containing site #2
Location Selection
2 data collection locations and 1 soil density control location are selected for each site.
At sites 1 & 2 the data collection locations are placed off center of the path to prevent foot traffic interference.
Control locations are 2 paces off the path for sites 1 & 2 and 2 paces from one of the data collection locations for site 3.
Determining Soil Density/Compaction
Insert a standard bulb planting tool into the soil up to the 2” markPlace soil from bulb planting tool into a standard 1 gallon freezer bagWeigh soil samples using a triple beam balanceDensity=Mass/VolumeDensity can be compared via mass measurements because all volumes should be constant
Insect Collection Procedures
1 pint glass jars are buried in the soil with lip even to the groundLeaves are tented over the jar opening to prevent outside interference in data collection Jars are left in place for 96 hour periods and checked for insects every 48 hours
Boat-backed Beetle
Common Black Ground Beetle
Invertebrates by Location
0
2
4
6
8
10
12
14
16
Boa
t-B
acke
d B
eetle
s
Com
mon
Bla
ck B
eetle
s
Cau
lum
bula
Sm
all S
pide
r
Mill
iped
e
Ear
wig
Uni
dent
ified
Ann
alid
Tot
al S
peci
min
s
Com
mon
Bla
ck B
eetle
Ear
thw
orm
Uni
dent
ified
Inse
ct
Sm
all S
pide
r
Uni
dent
ified
Bee
tle
Slu
g
Tot
al S
peci
min
s
Uni
dent
ified
Inse
ct
Sm
all S
pide
r
Mill
iped
e
Tot
al S
peci
min
s
Site 1 Site 2 Site 3
What it all means…
Is there a connection between soil density and invertebrate populations
size and diversity?
YES!
Conclusions:
1. Soil density has a visible effect on invertebrate
populations.
Human Activity
DensitySoil Compaction
Aeration
Drainage
Nutrient Content
Insect Population/Diversity
Conclusions:
2. For soil compaction to affect insect populations, the compacted area must be larger than the width of the paths chosen for this study.
3. The insect populations sampled for this study most likely reflect the populations found in areas with soil compaction equivalent to the control areas.